Bothrops insularis, commonly known as the golden lancehead,[3] is a species of extremely venomous pit viper in the subfamily Crotalinae of the family Viperidae.

The species is found exclusively on the island of Ilha da Queimada Grande, off the coast of São Paulo state, in Brazil.

[3] The common name of the species refers to the light yellowish-brown color of its underside and for its lance-like head shape that is characteristic of the genus Bothrops.

[3] The name "lancehead" refers to the distinctive head shape of all snakes in the genus Bothrops, which is somewhat elongated and comes to a point at the nose.

[6] B. insularis also has a longer tail than its closest relative, B. jararaca, which is most likely an adaptation to help the snake maneuver through the trees, and to eat larger prey like birds from a younger age.

[5] The quality of its habitat continues to decline due to vegetation removal by members of the Brazilian Navy who maintain the lighthouse on the island.

It is thought that the golden lancehead descends from a population of B. jararaca that became isolated on Queimada Grande, which was connected to the South American mainland during the Last Glacial Period, after a major sea level rise at the beginning of the Holocene.

There are no mammals native to the island Queimada Grande, which has undoubtedly had a profound impact on the evolution of the golden lancehead.

[3] In Campbell and Lamar's 2004 accounts of the venomous reptiles of Latin America, there was no mention of any predators that could potentially prey on an adult B. insularis.

[5] There are other fauna, such as frogs, lizards, and birds, on the island that eat invertebrates, but because insects are so plentiful in ecosystems, they may not be a limiting resource.

The golden lancehead is known to suffer from flukes (specifically Ochetosoma heterocoelium) in its mouth cavity as well as to carry the hard-bodied tick Ambylomma rotundatum.

[5] The Brazilian Navy has also contributed to habitat destruction by removing vegetation in order to maintain a lighthouse on the island.

[5] Because of these problems as well as overharvesting by overzealous scientists, Duarte et al. wrote that it is "very hazardous to assume that this is an invulnerable snake".

[5] In addition to intersexes, it has been observed that when compared to their mainland relatives B. jaracara, B. insularis have reduced fecundity in females, and high levels of mutations in male sperm, thought to be a product of heavy inbreeding.

[18] As of 2019, it was reported by snake expert Bryan Fry, in an interview with 60 Minutes Australia that the migratory birds that B. insularis depends upon were visiting less due to deforestation on the Brazilian mainland.

[20] However, considering the presence of potential prey susceptible to caudal luring[20] and the opportunistic nature of B. insularis,[5] it would not be surprising if this behavior were eventually observed.